WASHINGTON, D.C. — With funding for the federal government set to expire this weekend, congressional leaders and the White House have reached a deal on a $1.4-trillion spending package that would bolster election security, increase funding for wildfire fighting and, for the first time in more than 20 years, pay for gun safety research.

“I’m pleased that we have reached a bipartisan agreement that will keep government open, provide the certainty of full-year funding, and make strong investments in key priorities for American communities,” said Rep. Nita Lowey, the New York Democrat who leads the powerful House Appropriations Committee. “With higher spending levels in line with the bipartisan budget agreement, we are scaling up funding for priorities that will make our country safer and stronger and help hardworking families get ahead.”

The measure comes nearly three months after the start of the fiscal year, after months of contentious negotiations over spending priorities, set against the backdrop of House Democrats’ effort to impeach President Trump. The deal would ensure that the government stays open through the remainder of the fiscal year, which ends Sept. 30, 2020, while also enacting disparate initiatives and rejecting many of the cuts Trump had proposed.

Bills to fund the government at the end of the year have come to be known as “Christmas trees” because members of Congress attach pet projects, or “ornaments,” to the bills before they pass. Big or small, these add-ons have become even more important in recent years. After Congress ended so-called spending earmarks more than a decade ago amid scandals involving Republican members, lawmakers in a deeply divided Congress grasp for accomplishments to show their constituents they are getting things done. The add-ons increase the spending bill’s size and cost while the details are often opaque, even to the lawmakers who approve them.

Among the many provisions included this year is one that would raise the legal age nationwide for buying tobacco products from 18 to 21.

Another would repeal several taxes that were put in place to pay for Obamacare’s expanded health benefits and have been vigorously opposed by the health care industry ever since. They include the so-called Cadillac tax on expensive, generous health insurance plans, as well as a tax on medical devices.

California and other Western states still recovering from destructive wildfire seasons scored a major legislative win that was years in the making.

The new deal ends a long-standing practice known as “fire-borrowing,” which required the Forest Service to raid its other funds whenever it ran out of money to pay for fighting wildfires.

Faced with increasingly long and costly fire seasons, the Forest Service often wound up strapped for cash as a result of a firefighting budget that amounted to a fraction of what it actually cost to fight fires. With no choice but to continue paying firefighters, the agency used money that was supposed to pay for research, maintenance of national forests and preventive measures such as prescribed burns in forests.

“It would just eat up all of their resources,” said Jonathan Asher, a government relations manager at the Wilderness Society. “This issue impacted even people like biologists who would get funding to go out and study an endangered species or a critical habitat, and then all of the sudden, they would get into the month of July and be pulled off of it.”

If Congress approves the spending package, the Forest Service will be able to withdraw money from a FEMA emergency fund during especially severe fire seasons, just as the government does for hurricanes, tornadoes and earthquakes. The measure also increases funding for wildfire fighting by $1.9 billion over the previous year.

Lawmakers’ agreement denied the president a victory in his fight for a massive increase in border wall funding. Although the White House pressed for more spending, the end result maintains existing funding levels at nearly $1.4 billion for the U.S.-Mexico border, while giving the administration the leeway to pull money from other accounts.

This is far short of the president’s demands and what his administration would actually need to build the “big, beautiful wall” he campaigned on. The option to transfer money has also been complicated in recent days by a federal judge’s decision barring the president from using several billion dollars in military construction funds to pay for wall construction.

Democrats won $25 million to fund research on gun violence, a major accomplishment after decades of scarcely any federal investment in understanding one of the leading causes of death in the country. The spending deal directs the money to the Centers for Disease Control and Prevention and the National Institutes of Health.

Federal funding for gun violence research dried up in the late 1990s, after gun lobbyists pressured a Republican-controlled Congress to approve legislation, known as the Dickey Amendment, that barred the CDC from spending money “to advocate or promote gun control.” Although that didn’t explicitly ban research into gun violence, when coupled with budget cuts, it had a chilling effect on the field.

Over the course of the last two decades, the federal government has essentially walked away from efforts to investigate which policy changes or preventive measures would reduce gun deaths.

Some of this work has continued at universities or at the urging of state governments. In the aftermath of the San Bernardino massacre in 2016, the California Legislature decided to start funding gun research that the federal government wouldn’t support.

Attempts to revive federal spending took on a new sense of urgency in the aftermath of recent mass shootings.

The bills also include $425 million in new funding for election security grants — money that Democrats fought for in the aftermath of Russia’s meddling in the 2016 election, and evidence of its continued interference.

The money would be used to prevent cyberattacks and to help states and local governments harden their election infrastructure against possible digital interference in the 2020 election. This could include replacing old voting machines, particularly in states that still rely on machines that don’t print a paper record of each vote and thus leave no way to check if a digital tally has been sabotaged.